middlewares.py 文件源码

def _process_requests(self, items_or_requests, start=False):
        """Acquire the webdriver manager when it's available for requests."""
        error_msg = "WebdriverRequests from start_requests can't be in-page."
        for request in iter(items_or_requests):
            if isinstance(request, WebdriverRequest):
                if start and isinstance(request, WebdriverActionRequest):
                    raise IgnoreRequest(error_msg)
                request = self.manager.acquire(request)
                if request is WebdriverRequest.WAITING:
                    continue  # Request has been enqueued, so drop it.
            yield request